Characterization of Naturally Derived Polymer by Oxidative, Thermal, and Spectrometric Methods

Extensive use of fossil fuel for different purposes has resulted in significant depletion of it at an alarming rate. Therefore, a potential and sustainable alternative source are badly needed at this moment. Nowadays, lignocellulose biomass is appealing to much interest by the researchers because of its potential nature as a renewable carbon source. It is the most abundant renewable source which is composed of cellulose, hemicellulose, and lignin. Among them, lignin is considered the 2nd most abundantly natural polymer after cellulose which comprises 10-30 % of biomass depending on the source and the environment. Lignin is a three-dimensional cross-linked organic polymer, composed of three different phenylpropanoid units such as coniferyl, sinapyl, and pcoumaryl alcohols. Being a renewable and polyaromatic by nature, lignin is being considered as a potential source of a wide range of chemicals and renewable energy. But it is very important to understand the comprehensive structure of lignin before convert into value-added products. Therefore, our main aim is to characterize the naturally derived lignin by thermal, spectrometric, oxidative, and chromatographic techniques to understand the comprehensive structure and macromolecular features of lignin. To accomplish the goal, the objectives of this work are: 1. Optimize the processing conditions for the extraction of lignin from the non-wood source. 2. To investigate the thermal stability and functional groups of lignin and its residue by thermal and spectrometric methods. 3. To study the molecular weight distribution, and monomeric structure of lignin and its residue by chromatography. 4. Oxidative degradation of lignin into monomers and to optimize the reaction conditions for conversion. In chapter II, thermal behaviors of lignin and its residue after catalytic hydrodeoxygenation reaction were characterized by TGA and DSC. TGA results indicated that both lignin and its residue showed variable weight loss in different temperature ranges, different percentages of residual carbon, and different DTGmax of the sample. Results showed that the weight loss of residue was lower than the lignin throughout different temperature ranges. But a higher percentage of residual carbon (45.85 %) was observed for residue than lignin (25.89 %). On the other hand, the maximum rate of weight loss (DTGmax) for residue was observed at a lower temperature at 420 °C than lignin at 480 °C. DSC results showed a lower melting point for residue(150.48 °C) than lignin (174.40 °C). Moreover, the lignin-residue decomposed at 370 °C, whereas no visible change was observed in lignin around this temperature. So, DSC and TGA analysis revealed that lignin residue was thermally less stable compared to lignin. Additionally, lower melting point with higher residual carbon for residue showed that both thermally stable and unstable compounds were produced during the hydrodeoxygenation reaction. In chapter III, chemical structure, functional groups, and molecular weight of lignin and residue were investigated by FTIR, NMR, and GPC analysis. FTIR study, showed both lignin and residue contain the same functional group, and no further new band was noticed, which suggests residue still contains unreacted lignin or smaller breakdown products with similar chemical properties of lignin. NMR analysis also showed the same chemical functional group present in both lignin and residue. But the quantitative study of NMR showed a different amount of the functional groups. It was shown that lignin is higher in aromatic proton where the residue is higher in the aliphatic proton. Results also showed, aliphatic/aromatic ratio of the residue is 3 times greater than the lignin. The higher aliphatic/aromatic ratio of residue demonstrated that the significant number of aromatic moieties of the lignin have gone with the reaction mixture leaving the aliphatic moiety in the residue. On the other hand, GPC analysis found three distinct peaks for lignin and two for residue. The greater molecular weight distribution and polydispersity were observed which indicated the formation of C-C bonds during the catalytic reaction. The study showed that this kind of bond formation is related to the guaiacol units which are connected to each other at elevated temperature. In chapter IV, lignin and its residue were depolymerized by cupric oxide oxidation and monomeric products were identified and quantified by GC-MS analysis. A chromatographic study showed that lignin produced four monomers and residue produced two monomers, respectively where all of them are characterized as a G moiety. Among the phenolic monomers, vanillin was the major product for both samples. Additionally, the results showed residue contains less amount of vanillin and acetovanillone than lignin and no peaks for guaiacol and homovanillic acid. Oxidative depolymerization of lignin was also carried out at different temperatures and times to optimize the reaction conditions for better yield. The chromatographic study showed four monomers produced in each condition. Among them, vanillin was found as a major product and production of vanillin increased with the increase of both temperatures and times. The production of guaiacol and acetovanillone increased when the temperature reached 150 °C and time at 2 hours then slightly decreased with the increase of both temperature and time. But the production of homovanillic acid significantly decreased when the temperature reached 175 °C but slightly decreased when time reached 2.5 hours. Therefore, our oxidative study found 150 °C and 2.5 hours as an optimization conditions for the better production of phenolic monomers from lignin. In chapter V, lignin was extracted from wheat straw using an accelerated solvent extraction technique. To optimize the extraction conditions, extraction was carried at three different temperatures such as 140 °C, 170 °C, and 200 °C and two different acidic conditions 0.05% and 0.1% for 60 minutes. Then the extracted lignin was characterized by TGA, FTIR, and subcritical water. The study showed that extraction of lignin increased from 13.89 % to 28.69 % when the temperatures increase from 140 °C to 200 °C. But acid concentration showed very little impact on extraction of lignin. It was shown, extraction of lignin increased slightly with the increases of acid concentration at a specific temperature. On the other hand, characterization of lignin with TGA, FT-IR, and liquefaction showed the similar result with the commercial lignin, indicated lignin was successfully extracted from wheat straw. Liquefaction of lignin followed by GC-MS analysis showed 9 phenolic monomeric products with 86% total relative amount

Seniority, a problem of labor-management relations

Thesis (M.A.)--Boston University, 1946. This item was digitized by the Internet Archive

Was Blind but Now I See: The Argument for ADA Applicability to the Internet

This Note argues that the public accommodations provision of Title III of the Americans with Disabilities Act applies to the Internet. A broad reading of the public accommodation clause in Title III in conjunction with the supporting case law and the statute\u27s legislative history suggests that public accommodations are not limited to physical structures. Therefore, Internet companies that do not provide software compatible with the technology that visually disabled people use to access the Internet are liable for violating the ADA. The Note concludes with a summary of the first litigation on this issue between the National Federation of the Blind and America Online which was settled in July of 2000

Environmental Pursuits In Nanomaterial Systems Science With Indian Exemplars

The behavior and pattern of NPs of minerals in the evolutionary history of the earth vis – a –vis the environmental context are inquired into, with a riverine system as a model. The study of fractal dimensions of NPs of interest serves as an aid to obtain a comprehensive view of natural NPs in the model system. The present study combines inputs from work done on nanoparticles, derived from the Subanarekha River System and products of base metal mine effluents that are rich in NPs of minerals. The authors believe this study would help to establish certain universalities about NPs and provide an updated framework for understanding the current state of nanomineral science

Symptomatic vertebral hemangioma: Treatment with radiotherapy

Background: Vertebrae are the second commonest site among skeletal locations affected by hemangioma, but only about one per cent becomes symptomatic throughout the life. Though surgery, intra vertebral injection of various sclerosing agents have been tried in treating this benign process, no general consensus regarding management has been reached. Radiotherapy is emerging as a low cost, simple, non-invasive but very effective modality of treatment of symptomatic vertebral hemangioma. Aim: This study aims to find out the role of external beam radiotherapy in alleviating the symptoms of symptomatic vertebral hemangiomas without compromising the quality of life. Materials and Methods: Seven consecutive patients with symptomatic vertebral hemangioma were treated with a fixed dose of external beam radiotherapy; and muscle power was assessed before, after treatment and during follow-up. Results: All patients showed improvement of muscle power, which increased with the passage of time. Pain relief with improvement of quality of life was obtained in all the patients. Conclusion: Effect of radiotherapy on vertebral hemangioma is dose-dependent and the dose limiting factor is the spinal cord tolerance. In the present era of IMRT, greater dose can be delivered to the parts of vertebra affected by the hemangioma without compromising the spinal cord tolerance and expected to give better results

Efficacy of a combination of imidacloprid 10%/moxidectin 2.5% spot-on (Advocate® for dogs) in the prevention of canine spirocercosis (Spirocerca lupi)

The nematode Spirocerca lupi is a major canine parasite in warm regions of the world, classically causing parasitic nodules in the esophagus, aortic aneurysms, and spondylitis. This study evaluated the preventive efficacy of monthly treatment with imidacloprid 10%/moxidectin 2.5% spot-on (Advocate® for dogs) administered over a period of 9 months in young dogs naturally exposed to S. lupi on Réunion island. One hundred and twelve puppies, aged from 2.0 to 4.0 months and with a negative spirocerca fecal examination at inclusion, completed the study. They were randomly allocated to two groups. Group A puppies (n = 58) received nine spot-on treatments with Advocate® at the minimum dose of 2.5 mg moxidectin/kg bw at monthly intervals. Control group B puppies (n = 54) received no treatment for S. lupi. During the study, regular clinical and fecal examinations were performed, as was final upper gastrointestinal endoscopy. Endoscopy showed that 19 dogs from group B had spirocerca nodules, corresponding to a prevalence of 35.2% in dogs aged 12 to 14 months. In contrast, only one dog from group A had a nodule, corresponding to a preventive efficacy of 94.7% (p < 0.0001). None of the 378 fecal examinations were positive for spirocerca. This study confirms a high prevalence of canine spirocercosis on Réunion and shows that infestation occurs in very young puppies. Furthermore, it demonstrates that monthly spot-on administration of a combination of imidacloprid 10%/moxidectin 2.5% (Advocate® for dogs) in puppies starting at the age of 2 to 4 months achieves effective and safe prevention of canine spirocercosis

Nucleosynthetic osmium isotope anomalies in acid leachates of the Murchison meteorite

We present osmium isotopic results obtained by sequential leaching of the Murchison meteorite, which reveal the existence of very large internal anomalies of nucleosynthetic origin. The Os isotopic anomalies are correlated, and can be explained by the variable contributions of components derived from the s, r and p-processes of nucleosynthesis. Much of the s-process rich osmium is released by relatively mild leaching, suggesting the existence of an easily leachable s-process rich presolar phase, or alternatively, of a chemically resistant r-process rich phase. The s-process composition of Os released by mild leaching diverges slightly from that released by aggressive digestion techniques, perhaps suggesting that the presolar phases attacked by these differing procedures condensed in different stellar environments. The correlation between 190Os and 188Os can be used to constrain the s-process 190Os/188Os ratio to be 1.275 pm 0.043. Such a ratio can be reproduced in a nuclear reaction network for a MACS value for 190Os of ~200 pm 22 mbarn at 30 keV. We also present evidence for extensive internal variation of 184Os abundances in the Murchison meteorite. This suggests that p process rich presolar grains (e.g., supernova condensates) may be present in meteorites in sufficient quantities to influence the Os isotopic compositions of the leachates.Comment: 40 pages, 9 figures, 2 tables. Accepted for publication in Earth and Planetary Science Letter

Targeting Several CAG Expansion Diseases by a Single Antisense Oligonucleotide

To date there are 9 known diseases caused by an expanded polyglutamine repeat, with the most prevalent being Huntington's disease. Huntington's disease is a progressive autosomal dominant neurodegenerative disorder for which currently no therapy is available. It is caused by a CAG repeat expansion in the HTT gene, which results in an expansion of a glutamine stretch at the N-terminal end of the huntingtin protein. This polyglutamine expansion plays a central role in the disease and results in the accumulation of cytoplasmic and nuclear aggregates. Here, we make use of modified 2′-O-methyl phosphorothioate (CUG)n triplet-repeat antisense oligonucleotides to effectively reduce mutant huntingtin transcript and protein levels in patient-derived Huntington's disease fibroblasts and lymphoblasts. The most effective antisense oligonucleotide, (CUG)7, also reduced mutant ataxin-1 and ataxin-3 mRNA levels in spinocerebellar ataxia 1 and 3, respectively, and atrophin-1 in dentatorubral-pallidoluysian atrophy patient derived fibroblasts. This antisense oligonucleotide is not only a promising therapeutic tool to reduce mutant huntingtin levels in Huntington's disease but our results in spinocerebellar ataxia and dentatorubral-pallidoluysian atrophy cells suggest that this could also be applicable to other polyglutamine expansion disorders as well